Hi.
Here's my best understanding (which could be flawed, so I look forward to
finding out if I have missed something). Assuming that your time,
latitude, and longitude are all proper coordinate variables (no fill
values), either choice for the shape of your salinity variable works. If
you use the more complex shape, then you don't need to have the coordinates
attribute, as the relationships are declared through the shape. Speaking
of that, the coordinates attribute doesn't need to have PRESSURE in it.
Doesn't hurt anything, but it isn't necessary.
Having said all that, I find myself wondering why you are storing each
salinity profile in a separate file. Would you mind sharing what went into
deciding to take this approach?
Grace and peace,
Jim
On Mon, Apr 2, 2012 at 2:51 AM, andrew walsh <awalsh at metoc.gov.au> wrote:
> Hi CF list,
>
> We are working on coding up some 1000's netCDF files off CTD
> instruments and want to make usre we are following the
> latest netCDF conventions (v1.6) OK. As background the CTD records
> a profile pressure, temperature and salinity.
>
> Here is a summarised CDL version (not all attributes+variables+qc flags
> there, just majors for now)
> of what we propose:
>
> dimensions:
> TIME=1
> PRESSURE=729
> LATITUDE=1
> LONGITUDE=1
>
> variables:
> double TIME(TIME) ;
> TIME:standard_name = "time" ;
> TIME:units = "days since 1950-01-01 00:00:00Z" ;
> TIME:axis = "T" ;
> TIME:valid_min = 0. ;
> TIME:valid_max = 999999. ;
>
> double LATITUDE(LATITUDE) ;
> LATITUDE:standard_name = "latitude" ;
> LATITUDE:units = "degrees_north" ;
> LATITUDE:axis = "Y" ;
> LATITUDE:valid_min = -90. ;
> LATITUDE:valid_max = 90. ;
>
> double LONGITUDE(LONGITUDE) ;
> LONGITUDE:standard_name = "longitude" ;
> LONGITUDE:units = "degrees_east" ;
> LONGITUDE:axis = "X" ;
> LONGITUDE:valid_min = -180. ;
> LONGITUDE:valid_max = 180. ;
>
> double PRESSURE(PRESSURE) ;
> PRESSURE:standard_name = "sea_water_pressure" ;
> PRESSURE:units = "decibars" ;
> PRESSURE:axis = "Z" ;
> PRESSURE:valid_min = 0. ;
> PRESSURE:valid_max = 12000. ;
> PRESSURE:positive = "down" ;
>
> double TEMPERATURE(PRESSURE) ;
> TEMPERATURE:standard_name = "sea_water_temperature" ;
> TEMPERATURE:units = "degrees_C" ;
> TEMPERATURE:_FillValue = -99.99 ;
> TEMPERATURE:valid_min = -2. ;
> TEMPERATURE:valid_max = 40. ;
> TEMPERATURE:coordinates="TIME LATITUDE LONGITUDE PRESSURE"
>
> double SALINITY(PRESSURE) ;
> SALINITY:standard_name = "sea_water_salinity" ;
> SALINITY:units = "psu" ;
> SALINITY:_FillValue = -99.99 ;
> SALINITY:valid_min = 0. ;
> SALINITY:valid_max = 40. ;
> SALINITY:coordinates="TIME LATITUDE LONGITUDE PRESSURE"
>
> // global attributes:
> :conventions = "CF-1.6" ;
> :featureType = "profile"
> :cdm_data_type = "profile"
> + several other attributes later for ISO19115 metadata generation
>
> I am not sure if I should have TEMPERATURE and SALINITY arrays with 4
> dimensions
> like TEMPERATURE(TIME,LATITUDE,**LONGITUDE,PRESSURE) or just 1 dimension
> like I have above i.e. TEMPERATURE(PRESSURE). ?
>
> Any feedback on the above is greatly appreciated.
>
> Andrew Walsh
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> CF-metadata at cgd.ucar.edu
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>
--
Jim Biard
Research Scholar
Cooperative Institute for Climate and Satellites
Remote Sensing and Applications Division
National Climatic Data Center
151 Patton Ave, Asheville, NC 28801-5001
jim.biard at noaa.gov
828-271-4900
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